In recent years, the recording capacity and transfer speed of HDDs (Hard Disk Drives) have continued to improve at a rapid pace, making possible the recording and reproduce of moving-picture data, and audio visual data recording and reproduce apparatuses using HDDs have been developed.
FIG. 19 is a drawing showing a configuration of an audio visual data recording and reproduce apparatus using conventional technology. In the figure, reference numeral 190 denotes the audio visual data recording and reproduce apparatus, reference numeral 191 denotes a control circuit for performing input/output of audio visual data (AV data) with respect to the outside of the audio visual data recording and reproduce apparatus 190 and for operating each part of the audio visual data recording and reproduce apparatus 190. Reference numeral 192 denotes an actuator drive circuit, reference numeral 193 denotes buffer RAM, reference numeral 194 denotes a read/write signal processing circuit, and reference numeral 198 denotes an HDA (Head Disk Assembly) integrating a hard disk 195, head 196, and actuator 197.
As the basic operation of an audio visual data recording and reproduce apparatus using conventional technology and with this kind of configuration, AV data is recorded onto the hard disk 195 by temporarily storing AV data input via the control circuit 191 in the buffer RAM 193, and transferring it to the HDA 198.
The read/write signal processing circuit 194 detects the position of the head 196 on the hard disk 195 and transfers this to the control circuit 191. The control circuit 191 references this position signal, generates an actuator drive signal, and outputs this to the actuator drive circuit 192, whereupon the actuator drive circuit 192 outputs a drive signal to the actuator 197 inside the HDA 198. In accordance with this drive signal, the head 196 is positioned at the desired position on the hard disk 195, and AV data recording and reproduce can be performed based on a read/write control signal from the control circuit 191.
With a recording and reproduce apparatus using a hard disk, such as the above described audio visual data recording and reproduce apparatus 190, a loop recording function is implemented by using the high-speed accessibility of the hard disk (for example, Japanese Patent Laid-Open No. 9-139009 specification). A loop recording function constantly performs repeated overwriting of an image for a given time period in a prescribed area on the hard disk, thereby enabling the user to view an image back in time to a certain extent from the present time. For example, even if the record button is pressed when the scene to be recorded appears, the scene actually recorded will be delayed by around 5 to 10 seconds. Accordingly, it is useful always to record an image a little earlier than the image displayed on the screen, even if only 10 seconds or so, as described above.
In the above described audio visual data recording and reproduce apparatus 190, this kind of loop recording function is implemented by means of suitable control of the read/write signal processing circuit 194 and actuator drive circuit 192 by the control circuit 191.
On the other hand, a serial bus conforming to the IEEE (Institute of Electrical and Electronics Engineers) 1394 standard is coming into increasingly wide use as the standard interface for interconnecting general digital AV devices.
FIG. 20 is a drawing showing a configuration in which various kinds of AV devices and related devices are connected via an IEEE1394 bus. In the figure, reference number 190 denotes an audio visual data recording and reproduce apparatus; reference numeral 200 denotes a controller, implemented by means of a computer, for example; reference numeral 201 denotes a digital monitor for displaying AV data, which is digital data, as images; reference numeral 202 denotes a VTR which performs recording and reproduce AV data; reference numeral 203 denotes a tuner that selects a broadcasting station that is the AV data source, and outputs AV data; and reference numeral 204 denotes an IEEE1394 serial bus that connects the above described various devices and is used to exchange various signals comprising AV data and control commands.
As shown in FIG. 20, the various devices can exchange digital AV data, and control information such as commands controlling the connected devices, via the 1394 serial bus, and if, for example, control commands are issued using a personal computer as the controller 200, all the AV devices connected to the 1394 serial bus can be controlled by a single personal computer.
An example of the AV device control command set used on the 1394 serial bus is the AV/C (Audio Video/Control) command set. Using AV device control commands of this kind, the above described controller 200 can control the audio visual data recording and reproduce apparatus 190.
Now, conventional AV device control commands typified by the AV/C command set include, as commands that control recording and reproduce operations of the audio visual data recording and reproduce apparatus, a reproduce command to perform a reproduce operation, a record command to perform recording operation, a stop command to stop reproduce/recording operation, and a search command to change the recording or reproduce position on the hard disk.
In order to implement the previously described loop recording operation in an audio visual data recording and reproduce apparatus connected by an IEEE1394 serial bus interface, it is necessary to use a number of AV device control commands in concert.
FIG. 21 is a drawing showing the sequence of commands in the case where loop recording is performed in a prescribed area on the hard disk to enable implementation of loop recording operation using an above described conventional AV device control command set. Below, the procedure for executing loop recording operation by means of a conventional AV device control command set will be described with reference to this figure.
The controller 200 first issues a search command 213 to the audio visual data recording and reproduce apparatus 190. On receiving the search command 213, the audio visual data recording and reproduce apparatus 190 changes the AV data record position to the prescribed position on the built-in hard disk and sets up the AV data recording preparations.
Next, the controller 200 issues a video record command 214. On receiving the video record command 214, the audio visual data recording and reproduce apparatus 190 starts AV data recording from the prescribed position described above.
When the controller 200 confirms the location fixed as the end position in the prescribed area while AV data recording is being performed, it again issues a search command 213. On receiving the reissued search command 213, the audio visual data recording and reproduce apparatus 190 stops the recording operation, then returns again to a start of the prescribed recording area determined by the initial search command, and resumes the recording operation. Subsequently, recording is performed by having the controller 200 issue a search command 213 each time it confirms the prescribed last area, and performing repeated overwriting.
When the recording operation itself of the audio visual data recording and reproduce apparatus 190 is to be stopped, the controller 200 transmits a stop command 215. On receiving the stop command 215, the audio visual data recording and reproduce apparatus 190 stops the recording operation.
The procedure for implementing a loop recording function by controlling AV devices connected to an IEEE1394 serial bus by means of control commands in accordance with a conventional technology, then, is as described above. However, in this operation, the controller 200 constantly executes checks of the position of the area subject to loop recording, and issues a search command 213 numerous times in accordance with those checks, and thus a heavy load is imposed on the controller 200.
In addition, on the audio visual data recording and reproduce apparatus 190 side, since there is a time lag from reception of a search command 213 and command confirmation to the change of record position, there is a risk of gaps occurring in the AV data to be recorded.
Therefore, a function such as a loop recording function that repeatedly overwrites a given area with AV data cannot be said to be capable of being adequately implemented at the time of using a control command set in accordance with the above described conventional technology.
Further, when a recording or reproduce area of a prescribed size is designated for a specific use, as with loop recording, it is necessary to secure a recording area of the above described prescribed size on the hard disk, and to ensure that this is not used for other purposes. With an audio visual data recording and reproduce apparatus employing conventional technology, this kind of specific area is directly managed beforehand on the system side, and is differentiated from recording areas that can be used freely by the user via the controller, as with AV/C commands. That is to say, a control command for securing an area of the above described kind is not present in a conventional AV device control command set.
Thus, when an audio visual data recording and reproduce apparatus employing conventional technology is used connected to an IEEE1394 serial bus, there is a problem in that the user cannot control the loop recording function, or a function for designating a recording area flexibly according to its use, via the controller.